Not long to go now until Mercedes-Benz shows its new 2018 A-class. We’ve caught various prototype iterations, as engineers continue to hone the new underpinnings which are upgraded from the current A's platform.

These new shots give us our best look yet, although many design details are still hidden, despite lighter camouflage than before. Expect much of the styling to take its cues from the Concept A Sedan displayed at the 2017 Shanghai show.

Several A-class pre-production prototypes were seen testing with competitor vehicles in tow, including the VW Golf seen in some of the pictures.

The new A-class has been designed to incorporate more alternative powertrains and is said to have a longer wheelbase for extra interior space. Read on for everything you need to know about the next-gen A-class range.

What’s the 2017 A-class like inside?

We've managed to snaffle some new spy photos spilling the interior secrets of the new A, which looks set to offer a cut-down version of the electro-display wizardry from bigger Mercs.

These scoop pictures reveal a wide, twin-screen digital display instead of conventional dials, a trio of cool-looking round air vents dominating the central stack and some much higher quality metallic switches for heating and ventilation. Keyless ignition is also fitted.

Early spyshots suggest a wide, dual-screen digital instrument layout along the lines of the S-class and E-class. Plenty of physical buttons on the steering wheel, however…

If you’d previously been tempted by the Mercedes A-class, but found it wanting in terms of space, then you’re in luck as the fourth-gen version is set to offer more room inside.

Will there still be a nutty AMG version?

The high-performance all-wheel-drive Mercedes-AMG A45 will return, and its 2.0-litre four-cylinder turbocharged engine’s power output is expected to top 400bhp this time around. That’s a huge amount from such a small capacity, and a healthy increase over the current A45’s 376bhp.

The high-end superhatch market has seen power outputs soar in recent years, with Audi’s latest RS3 offering 395bhp from its 2.5-litre five-cylinder engine, and BMW’s M140i 335bhp from its 3.0-litre six.

What is thought to be a prototype for the next A45 is pictured below, and elsewhere in this story's gallery.

The new AMG A45 is expected to join the new A-class range several months later than the regular models, most likely in late 2018.

Although the A45 prototype pictured above features a single exhaust outlet on each side, the production car is expected to get quad pipes, along with a larger, less subtle rear wing. And probably not a tow bar as standard - that'll be for transmission durability testing on this test hack.

The warm hatch version: is Merc preparing an A40 AMG?

Our new spy photos follow on from earlier shots of Mercedes-Benz A-class prototypes testing in southern Europe. One of the cars was a higher-performance version, but not quite the replacement for the all-singing, all-dancing A45.

Spotted testing with a variety of other AMG production cars and prototypes, this go-faster model (pictured above) is thought to be an upcoming A40 variant, a circa-300bhp competitor to the likes of the Audi S3 and VW Golf GTI. Clues as to its uprated performance over cooking A-class models include a large additional air intake in the front bumper, larger ventilated brake discs and two exhausts at the rear.

Our original set of spy shots showed the new A-class being tested in southern Europe, while CAR reader Chris Ellen also spotted the Mercedes out on the road in Germany – and supplied us with many of the shots in the gallery above.

How will Mercedes tweak the A-class to offer more room?

Mercedes’ upcoming hatch will reputedly ditch the current A-class’s MFA platform for a new version, dubbed ‘MFA2’. It grants a longer wheelbase, increasing interior space.

The new MFA2 platform will also also be slightly lighter than the outgoing platform, and offer more flexibility when it comes to powertrains.

Are there any other big changes?

The rear light clusters have been redesigned, judging by the spy shots. In the current A-class they’re a wide one-piece design, resulting in a narrow opening in the tail – meaning it’s hard to load bulky items.

It looks to be the case, however, that the new car will feature split tail lights, with standalone clusters in the tailgate and rear wings – making the aperture wider, improving access to the A-class’s boot.

Mercedes is also planning a four-door version of the A-class, this time around – but we’ve no official word as to whether this’ll make it to the UK yet.

Any new engine options this time around?

There’ll be the obligatory four-cylinder petrol and diesel options, as well the aforementioned AMG derivatives.

Mercedes may also roll out a three-cylinder petrol version of the fourth-gen A-class, along with a plug-in hybrid version ideal for company car drivers – or those regularly driving in London.

Will the MFA2 platform be used in anything else?

It’s expected to find its way under the next generation of CLA, B-class and the mooted upcoming GLB SUV.

When’s this new A-class due?

It’s expected to arrive in September 2017, at the Frankfurt motor show, ahead of deliveries in early 2018.